Draft version 5.0, May 26, 2005

WATER CAN FLOW UPHILL: A NARRATIVE OF CENTRAL ARIZONA

Charles L. Redman and Ann P. Kinzig

Arizona State University Central Arizona–Phoenix (CAP) LTER

Introduction This narrative, the Arizona case study of the “Ag Trans” project, explores the relationship between ecological and human systems in the Salt River Valley of central Arizona over the past millennium, focusing upon the 140-year period of Anglo-American settlement. Our subject matter is the changing mosaic of Sonoran Desert landscapes, irrigated farmland, and urban settlement. We examine how evolving patterns of perception, valuation, and use of water and land have been influenced by and, in turn, have influenced climate, environment, settlement, and agrarian landscapes. The logic for studying this region is strengthened by its presence within the Central Arizona–Phoenix Long Term Ecological Research (CAP LTER) project. Our research perspective derives from two underlying concepts: 1) human management of surface and groundwater resources in this arid region has fundamentally altered both natural and human-modified landscapes; and 2) the technological and social aspects of this relationship have advanced over a relatively short time and are proceeding rapidly. Hence, this locale comprises an excellent laboratory for examining the interplay between ecological and human systems. The context for this case study is the rapidly urbanizing region of Phoenix, set in the Sonoran Desert of the US, in a broad, alluvial basin where two major tributaries of the Colorado, the Salt and Gila rivers, converge (Figure 1). The basin has known continuous, and often extensive, agricultural activity for over 1,500 years, when it was first settled by an irrigation-based society known as the Hohokam. Anglo occupation and agricultural activities began in 1867, with excavation and use of former Hohokam canals. By the late 19th century, the pattern seen across the core of the Salt River Valley was a broad extent of farms with access to irrigation water, served by seven small communities centrally located among the farms. In ensuing decades, those towns expanded to form a contiguous metropolitan area, with concomitant spread of farmland into adjacent flatland farther from the river, yet still within range of gravitation-fed irrigation. The latter half of the 20th century witnessed rapid growth in the region—nearly three times the national average (Figure 2)—at the cost of surrounding farms and desert landscapes. Over the past 25 years, more than half the region’s highly productive farmland has been lost to urban development (Figures 3 and 4), with much of the remaining farmland within commuting distance of the urban fringe expected to be lost in the next 25 years. At the same time, farmland conversion has not met the demands of a burgeoning population, with most new housing in the past three decades being established on former desert lands. These historic trajectories have led to significant spatial variation in vegetation and structure of residential and remaining desert landscapes (Figure 4).

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The challenge for this narrative, and for CAP LTER in general, is to systematically study rapid urbanization in central Arizona, a region that includes Phoenix, four of the state’s five next-largest cities, and over 500,000 acres of highly productive, irrigated farmland. The conversion of farmland to urban and suburban development is a nationwide issue, with over 50 acres per hour being lost to this process (USDA 2001). Therefore, our overarching goal is to build a qualitative and quantitative understanding of the patterns and processes that underlie long-term alterations to the ecosystem and the function of changing landscapes. For an urban ecosystem and its surrounding region, achieving this goal hinges on unraveling the complexities of intense human participation in the system—with attendant economic and social drivers, radically altered land cover, accelerated cycling of materials, and heretofore underresearched ecological impacts of a built environment (Redman 1999; Grimm and Redman 2004). The study of agrarian landscapes in transition is an integral component of the urban ecology of the region. This improved understanding positions us to better grasp the opportunities and challenges facing those crafting conservation strategies for the region. The presence of intensive agriculture for over a century and rapid urbanization have led some environmentalists to give up on this region as having been subjected to excessive human manipulation. However, the presence of so many people provides a chance to acquaint residents with the value of conserving or restoring desert and riparian habitats, the ecosystem functions that support these habitats and the human presence as well. An ample prehistoric and historic record of land-use and settlement enriches the lessons that conservation projects can communicate to the general population. Two special challenges face the conservationist in an urban region, however. First, even if habitats are set aside for conservation, the conservation plan will need to accommodate heavy visitation and recreational opportunities. Second, because humans have modified virtually all landscapes in the region, planners must decide what characteristics to favor in restoring the landscape. These types of decisions are faced in the design of almost all “nature” preserves but, when a preserve is situated on a highly transformed agrarian landscape or close to an urban center, the gravity of these decisions is more transparent. The Ecological and Conservation Context The Phoenix Basin is situated in the Sonoran Desert, which extends through southern Arizona into southeastern California and covers most of the Baja peninsula and the state of Sonora in Mexico. The Sonoran Desert is lush compared to other deserts, with the greatest diversity of plant life of any desert in the world. Despite such diversity, two distinctive plant types are most often associated with this desert—leguminous trees and large columnar cacti (including saguaro and organ pipe). The Sonoran Desert houses 2,000 species of plants (about half of which are annuals), 550 vertebrate animal species, and unknown numbers of invertebrates (Arizona-Sonoran Desert Museum 1999). Phoenix is situated in a subdivision of the Sonoran Desert known as the Arizona Uplands. Characterized by many mountain ranges and interspersed valleys, it is the highest and coldest Sonoran subdivision and is the only one that experiences hard frosts. The dominant upland vegetation types are saguaro-paloverde “forests” on outwash slopes and pediments, with creosote bush dominating lower, flatter areas, and mesquite-dominated communities occurring in the meandering riparian zones of the Salt and Gila rivers (Figure 5).

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The region experiences two rainy periods each year. Winter (December to March) frontal storms originate in the North Pacific and bring relatively gentle rains. The summer (July to mid-September) monsoons originate in the Tropics, with rain often delivered in violent thunderstorms. Rainfall is thus both spatially and temporally variable across the desert. The Phoenix area averages less than 200 mm of rainfall per year, with nearly two-thirds delivered across the two (roughly equal) rainy seasons (www.worldclimate.com). Limited rainfall in the Phoenix Basin necessitates irrigation agriculture. Modern agriculture concentrates along the Salt River, which is formed in eastern Arizona by a confluence of the White and Black rivers. The Salt drains an area of about 5,130 square miles, with the northern boundary of the catchment defined by the Mogollon Rim, a 2,000-foot escarpment that forms the southern boundary of the Colorado Plateau. The Salt River is joined by the Verde, which drains an additional 6,188 square miles. Below its confluence with the Verde, the Salt River on average delivers over 1-million-acre feet of water per year (1.23 MAF), with relatively high year-to-year variability. Streamflow reconstructions of Salt River flow from 572 to 1450 AD, for instance, show a slightly lower average streamflow of about 1.15 MAF per year, with a standard deviation of 0.64 MAF (Figure X in Graybill et al. 1999). Below-average streamflow is more common than above-average (56% versus 44%), and long periods of drought are not uncommon (Figure 2 of 10-year averages in Graybill et al. 1999). The Gila River originates in the highlands of New Mexico and traverses south of Arizona’s White Mountains before descending into the floodplain where it begins to be used for irrigation. Although the Gila watershed is almost as large as the Salt’s, differences in topography and precipitation result in a mean annual discharge (0.354 MAF) less than one-third of the Salt’s (Figure11 in Graybill et al. 1999). The river’s annual distribution of discharge also differs markedly. Winter precipitation in the upper elevations (flow increases steadily beginning in November, usually peaking in March or April) determines the annual discharge of the Salt. It has a secondary, but less significant, peak in late summer due to seasonal rainfall. In contrast, the Gila River discharge reflects summer rainfall much more and exhibits a markedly bimodal annual distribution (Figure X in Graybill et al. 1999). Modern (post-1867) human activities, including agriculture, in the Phoenix Basin have adversely affected many species. In Maricopa and neighboring Pinal and Pima counties, 19 species are classified as endangered (7 plant, 5 fish, 4 bird, 3 mammal), and 4 as threatened (2 fish, 1 amphibian, 2 bird) (AZCF 2005). Agricultural activities that have contributed to the demise of these species include land conversion, removal and redistribution of water from stream courses, alterations of riparian habitats, grazing, pesticide use, and species introductions. Central Arizona has benefited from a long history of public-land conservation that predates statehood. In 1905, the Tonto National Forest (northeast border of the CAP LTER study area) was created to protect the Salt and Verde watershed; it’s three million protected acres represent the fifth-largest forest in the US. The Tonto National Forest has preserved, at a low population density, a large proportion of the upland watershed of the Salt River Valley that is the subject of this narrative. With statehood granted in 1912, much of the remaining landscape of central Arizona that was not settled or part of an Indian reservation was allocated to the State, to be held for the benefit of public education, or to the Federal Bureau of Land Management (BLM), to be

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managed for multiple uses. This land has been leased for commercial uses and recently became the center of controversy on how much land the state should sell for residential development or hold for conservation value. The BLM lands have largely remained in public hands, with some lands sold to the city and county park systems and some transferred into National Monument status. In 1924, prominent local citizens, with the help of Senator Carl Hayden, bought 16,000 acres of BLM lands to establish South Mountain Park in Phoenix, renowned as the largest municipal park in the country. In 1935, the National Park Service developed a master plan for the park, with riding and hiking trails, picnic areas, and overlooks of the city. The Civilian Conservation Corps built many of the plan’s facilities, and the park now has an annual visitation over three million. The Maricopa County Park system began in 1954 to preserve the mountain areas surrounding the rapidly growing region for future generations. In 1970, the Federal Recreation and Public Purposes Act allowed the county to purchase thousands of acres of parkland from the BLM at $2.50 an acre so that today, through a combination of leases and purchases, the system has 10 regional parks totaling more than 120,000 acres. East of the CAP LTER site are the majestic Superstition Mountains, where it is said that disaster stalks any who travel there, such as the mysterious Lost Dutchman who was further said to have abandoned a fabulously rich mine never to be rediscovered. The wilderness value of the Superstitions has long been recognized, and 160,000 acres were established as a Primitive Area in 1939 and designated a “Wilderness” in 1964, protecting them from urban encroachment. The most recent Federal lands to receive additional protection were a series of National Monuments created largely on BLM lands in the waning days of the Clinton presidency. Of these, the Agua Fria National Monument north of the CAP LTER site, is particularly important. Established to preserve a rich archaeological record of prehistoric occupation from urban sprawl, this 71,000 acre monument also serves to protect the rugged canyon and riparian area of the Agua Fria River, which supplies agricultural and residential water to the west side of our study area (Figure 6))

The Nature-Human Conceptual Conundrum Once people settled permanently in central Arizona and redirected the hydrological cycle to enable irrigation agriculture, separation of the natural environment from its human-engineered counterpart grew complex. In the course of altering land and water to suit economic needs, people often destroy much of what one would consider “natural.” Although irrigated landscapes are in some sense artificial, they are constructed with topography, climate, and soil characteristics as guideposts. Hence these early agrarian landscapes are sometimes thought of as “modifications” of the natural order, while more intensive construction is considered to have created an anthropogenic landscape. We believe that there is no clear dividing line between the natural and anthropogenic, only a continuum of complex sets of relationships. To simplify the semantics of this narrative, we will use the term “nature” to distinguish processes and conditions that have minimal human participation from those where the human impact is substantial. This division is not to suggest that humans are not part of nature, but to permit a contrast that will have intuitive meaning to a large audience. However, we do not intend to suggest that nature is a passive canvas upon which people built their idealized world. Quite the contrary, we assert that nature is a vigorously reactive and creative force. As the construction of an irrigated landscape degrades habitats, it creates others, such as reservoirs, canals, and fields that provide homes for new species that establish new hydrological relationships. Nature does not disappear in the face of anthropogenic activities but is transformed into new and, perhaps, novel ecosystems.

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During the early years of Salt River Valley settlement, irrigation agriculture was communicated to prospective immigrants as a great human accomplishment (Figure X: chamber of commerce image or photo). With irrigation, settlers could transcend nature’s limits and farmers could be liberated from their dependence on precipitation. Advocates portrayed early irrigators as modifying the landscape so that the land could reach its potential, referring to farmers in a religious sense, as “understudies of the Creator” (Fiege 1999:23). The farmer need not fear drought; the Master Irrigator could “make water flow uphill” (Fiege 1999:11-22). Despite idealized expectations, settlers found a far-different reality. Irrigation agriculture involved constant interaction among people (with their aspirations, technologies, and labor) and the uncertainties of nature. Triggering Events and Human Response We divide the socioecological history of the region into four eras, representing major transformations in the relationship between residents and their environment. We categorize these eras as the Native American Years, Emergent Years, Boom Years, and Southwest Metropolis Years (see Luckingham 1989). Multiple factors drive agrarian landscape transformations, including climatic uncertainty, soils, population dynamics, economics, politics, technology, values, and evolving popular perceptions. Rather than discuss these factors in isolation, we treat them as interrelated factors that became key triggering events (both crises and opportunities) in each era. The perception, impact, and response to these events acted on local, regional, and national scales, occurred at differing tempos, ranging from rapid to sustained, and led to impacts on, and elicited responses from, the local coupled human-natural system. In Table 1, we present the eras and the triggering events that characterize them. We employ the term “events” broadly, to encompass actual events, more sustained forces, policy changes, and opportunities upon which settlers could act. People within a society hold shared ideas about how their socioecological system works and how to respond to a variety of inputs. We refer to these shared ideas as the mental model held by that society at that time. These mental models may derive from a variety of sources―textbooks, government agencies, or personal experience, to name just a few. We concentrate here on the prevailing mental models for each era, though these prevailing models were almost certainly not shared by all members of a society at any given time. Some mental models would be pervasive (e.g., best to plant crops in the spring); others might be held mostly by the powerful (e.g., best to lobby elected officials to pass favorable legislation). These prevailing mental models, though, would have defined the set of appropriate responses to a perceived challenge or crisis; the ecological or social changes derived from these responses may, in turn, have altered the prevailing mental models (van der Leeuw and Redman. 2002).

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The Native American Years (and Spanish Colonization to the South) The advent of adequate irrigation technology (Table 1: NA1) around 500 AD prompted the first substantial occupation of the lower Salt and Gila rivers’ alluvial plains, signaling the era’s first triggering event. Before this time, sparse rainfall and high summer temperatures discouraged settlement in the lowland river valley. By 1000 AD, an irrigated subsistence regime had transformed a virtually unoccupied landscape into one of North America’s major prehistoric population and cultural centers (Bayman 2001; Crown and Judge 1991). Hohokam villages were established across a broad area of the Sonoran Desert, with more dense settlements in the lower Salt River Valley, in the vicinity of modern-day Phoenix. The Hohokam used an elaborate suite of agricultural strategies focusing on water control and irrigation technology. They built hundreds of kilometers of canals, including one canal exceeding 24 km. In addition, we now believe that the Hohokam constructed reservoirs (some based on former canals, others more pond-like) to store water during low-water months. Distinctive styles of craft production, architecture, and mortuary practices marked the crystallization of the Hohokam tradition. Communities of dispersed clusters of pit houses were situated along the canals, distinguished by what archaeologists have interpreted as ballcourts. Population estimates vary widely, but as many as 10,000 people likely occupied the Salt River Valley and farmed much of the same land that Anglo-American settlers would come to use in the late-19th century (Figure 7). The basic agricultural product in the Salt River Valley was maize, with the region offering higher yields and the possibility of two growing seasons per year (Van West and Altschul 1997). Maize

Table 1. Triggering “Events” in the Interaction of Population, Agriculture and Environment in Central Arizona Native American Years (500-1866) NA1: Advent of adequate irrigation technology and infrastructure colonized the relatively empty, but potentially productive, Salt

and Gila river valleys. NA2: Shift in climate and associated surface-water flow prompted the Preclassic to Classic transformation in social, political,

and economic organization. NA3: Diminished resilience of sociopolitical organization made system vulnerable to minor perturbations. Emergent Years (1867-1940) E1: Opportunity presented by an occupied, potentially productive agro-ecological niche (irrigable lower Salt River Valley) for

producing crops to supply local soldiers and miners led to re-excavation of prehistoric canals and success in establishing agriculture.

E2: Catastrophic floods in 1890-1891, followed by severe drought from 1897-1903, drew cooperative action and use of federal funds to build the first major reservoir.

E3: World War I spiked demand for locally mined copper and locally grown cotton, leading to a boom in population, agriculture, and commercial activity (Figure 11).

Boom Years (1941-1970) B1: World War II generated military industry, air bases, and new infrastructure, familiarizing people with the region. B2: In 1948, Motorola built an electronics facility in the Valley, the first step in a process that would reshape the region’s

economic base, attract an influx of people looking for good jobs, and transform its rural character. B3: Popularity of large housing tracts that provided air-conditioned and economical dwellings, created a suburban ambience

that now characterizes the entire urban area. Southwest Metropolis Years (1971-present) SM1: National migration to the Sunbelt encouraged population, industrial, and commercial growth. SM2: The Groundwater Management Act, enacted in anticipation of a cut in federal funding, reversed the expansion of farming,

thus decreasing agricultural acreage and diverting water from agriculture to the urban sector (Figure 18 and 19a). SM3: Increased migration from Mexico and Central America changed the demographic character of the city. SM4: Drought of 1999-present, combined with concern over quality-of-life issues, may inaugurate a shift in the belief that

population growth is a necessary engine driving the city’s economic viability.

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was supplemented with cotton, beans, and squash, crops that show up less in the archaeological record, but were almost certainly key to the agricultural regime. Agave cultivation for both food and fiber was common and required less water than maize (Bayman 2001). Agave was likely grown both in the upland areas where irrigation canals could not reach and possibly as field boundaries in the low-lying maize areas. The Hohokam foraged to supplement their diet with seed-bearing trees (mesquite), fruit-bearing cacti (prickly pear and saguaro), and hunting (rabbit, deer, and bighorn sheep). In addition, fish and rodents were locally available and provided a significant proportion of the protein in the Hohokam diet. The second triggering event of the Native American Years coincides with the transformation of socioecological landscape during what archaeologists characterize as the Classic period (1150-1450 AD). A shift in climate and associated streamflow (Table 1: NA2) exacerbated a series of slow changes in the sociopolitical context, thus promting the landscape transformation. The resulting social, political, and reorganization involved the rapid abandonment of many ballcourt villages and the construction of new monuments—platform mounds and Great Houses (Abbott 2003). Populations concentrated along perennial water sources in aboveground, enclosed compounds and, with some exceptions, nonriverine deserts were eventually abandoned. Although the irrigation canal system appears similar in these two periods, it is likely that the sociopolitical organization became more hierarchical and the settlements more tightly aggregated. Over time, the focus of Hohokam settlement and farming shifted to canals that ran along slightly higher terraces somewhat farther from the river course. With this shift came an increasing reliance on upland and nonriverine areas, including the introduction of irrigation agriculture in the upstream Tonto Basin. In the Salt River Valley, maize agriculture continued to dominate the diet, but a significant shift in faunal resources may reflect an overexploitation of local resources (James 2004). There appeared to be a decreasing dependence on large game (deer and sheep) and a decrease in the size of the fish (chubs and suckers) consumed. We are only now detailing the process of Hohokam decline, but there is human skeletal evidence suggesting that their nutrition was worsening and overall health was decreasing (Abbott 2003). It should be noted that the significance of these factors and the relationship of declines to overexploitation and decreasing agricultural productivity has yet to be securely demonstrated. It is clear that, by 1450 AD, the major river valleys, especially the Salt River Valley, were largely abandoned and the region’s overall population had diminished significantly. We consider this response—the diminished socioecological resilience of the Hohokam—the third triggering event of the Native American Years—(Table 1: NA3). The slow-moving aspects of this “event” likely included straining their exploitation system, accumulating excessive wastes (e.g., salinization, soil compaction), and developing vulnerabilities in their sociopolitical responses (diminished flexibility, constrained movement, expanded hierarchy). These factors may have reached a point where an external trigger such as flood or drought, which might have been absorbed under previous regimes, led to socioecological collapse. For the next 400 years, the population of the Salt River Valley was depleted and much of the natural vegetation and hydrological regimes reasserted themselves. Ongoing archaeological investigations focus on the ecological legacies of irrigation agriculture, which the Hohokam practiced for centuries (Reference).

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The Spanish explored what is now Arizona in the 16th century; establishing early settlements in the far south of the state late in the 17th century. Settlement focused along the Santa Cruz River, with presidios and small settlements established up to the Gila River. With Mexican independence in the early 19th century, interest retreated to the presidios and missions in the south. By 1846, there were only 1,000 Europeans living in these settlements (Schmieding unpublished manuscript). Pima Indians continued to farm along the Gila River, with early Anglo-Americans encroaching upon the surrounding area to trap and mine. Towns were eventually established at the upstream edge of the Gila’s alluvial plain at Andersonville and Florence, whose inhabitants diverted much of the seasonal flow to their own fields and thereby denied water in dry years to downstream settlements of Pima Indians. The image of the region conveyed to prospective settlers was the desert myth of the American West: harsh environment, hostile Indians (i.e., Apache and Yavapai), and farming that challenged the imagination (Figure 9). Since the almost complete abandonment by the Hohokam in the 14th or 15th century, central Arizona remained virtually unoccupied even as Pima, Spanish, and Anglo-American activity continued to the south. The mining boom of 1861-62 brought prospectors further north and, though they did not settle in the lower Salt River Valley, they did locate in the surrounding highlands, laying the foundation for expanded settlement. The Emergent Years Our narrative begins in earnest in the Salt River Valley in the 1860s, occupied by a few Pima Indians who farmed along the river and by more mobile Indian groups (Papago and Apaches), and visited by a few Anglo-American trappers and miners. The Salt River flowed in episodic fashion, with heavy floods contrasting with low flow periods, via a meandering channel down the center of a large, extremely flat, alluvial valley broken only by isolated outcrops of buried mountain chains. In 1864, the General Land Office commissioned a regional survey that details the vegetative communities of that time (Figure 10). There were cottonwood/willow in the riparian areas, mesquite bosques along the margin of the first terrace, following some former canal alignments and up intermittent tributaries, creosote-salt bush in the flats (perhaps less vulnerable to flooding), and paloverde-saguaro on the bajada slopes and mountain remnants. The first triggering event we highlight is the opportunity presented by a potentially productive, yet unoccupied agro-ecological niche (Table 1: E1) for producing crops to supply soldiers and miners. The US Cavalry had established the Fort McDowell outpost at the upstream margin of the floodplain to limit Apache movement. Because there was virtually no farming in the Valley at that time, the Fort had to import its food and fodder at a substantial expense. In 1867, Jack Swilling, an adventurer who served in the Mexican, Civil, and Indian wars and then tried to promote mining and farming north of the Salt River, recognized traces of prehistoric Indian irrigation ditches along the Salt River. Swilling was quick to realized that these ditches afforded a prospect to grow food and fodder locally. He and his colleagues dug out one of these canals, grew crops, and initiated the farming settlement that eventually grew into Phoenix, now the fifth-largest city in the US. In the next 20 years, Swilling and other white/Anglo settlers re-excavated ancient canals, dug new canals, and rapidly established farmlands, demonstrating the impressive agricultural potential of the Salt River Valley. The farming community grew quickly and Maricopa County was established in 1871 with Phoenix as its county seat. Another change impacting the growing perception of the desirability of farming was the Desert Land Act of

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1877. This legislation increased the land area of an initial homestead from 160 to 640 acres, recognizing that, to make a go of it, a larger track of land was needed in these arid lands than in the Great Plains states where homesteading had begun. This first “event” built upon local ecological conditions and available agricultural know-how, precipitated by an abrupt change in local settlement patterns. This change created an opportunity for economic gain through investment that would establish irrigation agriculture in the region. A shift in perception had occurred: from linking the economic potential of the Salt River Valley to mining, to recognizing that irrigation farming offered vast economic opportunity in a seemingly inhospitable desert. This shift in regional perception may be considered part of a much larger phenomenon that characterized the entrepreneurial spirit and western movement following the Civil War. The local management response, carried out in part by Civil War veterans, was to seek their riches by reestablishing irrigated farmlands in the Salt River Valley. More than planting new crops occurred, the response was to transform the local hydrology, flora, fauna, and human settlement, and thereby redefine the potential opportunities and eventual vulnerabilities of the landscape. Although early farmers proclaimed their success, their task was difficult, and their transformation of the landscape was not as complete as they wished. Just as farmers took advantage of natural features such as topography and soil, nature took advantage of the changed hydrology engendered by the irrigation canals. In some ways, canals functioned as ecosystems analogous to rivers, carrying sediment and dissolved substances, and supporting fauna and flora of their own. Riparian areas developed along their banks that would house their own characteristic assemblages of fauna and flora. Some of these changes must have provided the landscape with a pastoral charm, especially for new settlers who had arrived from more temperate locations. Algae, cattails, other water plants, and fish would thrive in the canals while grasses, shrubs, and willows would have grown along the canal banks attracting waterfowl, ground squirrels, and other small mammals. Despite the positive aesthetic aspects of this “created nature,” these colonizing organisms diminished the efficiency of the canal for agriculture: by absorbing water from the canal, firming the canal banks in some places while weakening them in others, and slowing the flow of water. In addition, evaporation from canal surfaces (the annual pan evaporation rate in Phoenix is now 200 cm a year) and ground seepage (estimates range from 30-60% for unlined canals) would reduce the water available for crops and thus alter the local environmental characteristics. Removing water from the main channel of the Salt River also changed the characteristics of the river itself. With diminished volume, the Salt may have meandered more broadly; with heavier sediments, more dissolved nutrients, and a straighter channel coming only during floods. However, the people who built head gates to capture water for their canals and who lived or farmed near the rivers would probably have worked to keep the river within as narrow and fixed a channel as possible by encouraging the formation of leveés and other means. The redesign of the landscape by irrigators created unintended responses from natural forces and changes in their own social relations. The second half of the 19th century in the US was a time of unbridled capitalism; many heading West were not only seeking their own piece of land to farm, but hoping to benefit as entrepreneurial land speculators. Although private property and individual water rights allocated according to the principle of “prior appropriation” were at the

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very foundation of the early settlement of the region, these principles were not always consistent with the conditions the natural regime established. Prior appropriation was the basis of the legal principle that the first settlers along the river had first call on withdrawing a reasonable quantity of water based on their continued use of this water. Although farmland may have been divisible into finite units for individual ownership, water that gave value to the land did not divide as easily. For example, if a downstream farmer had water rights before the upstream farmer, during a dry year without enough water for both farmers, only constant vigilance (and perhaps armed conflict) would keep the upstream farmer from taking enough water to avoid calamity for his fields and family, thereby depriving water to the downstream farmer with the “superior” water rights. Scenarios such as these led to informal agreements and early legal policy on water distribution, such as the Howell Code and the Kibbey Decision, which provided a baseline for water-rights adjudication (Schmieding, unpublished manuscript). Other examples of ecological processes that encouraged collective action were the spread of pests overland, algae growth in the canals, or salinization of fields due to rising groundwater. In each situation, individual farmers would need the cooperation of all farmers in an area, or perhaps even the entire valley, to adequately redress the problem. Although there was clear competition between major players, cooperative action was an early hallmark of irrigation farming in the Salt River Valley, leading to the creation of social, economic, and political institutions that reflected collaboration as the dominant local solution to these pressures (Smith 1986; Kupel 2003). Why did cooperation dominate over conflict? Three possible explanations could be advanced at this point: first, there was more potential farmland and available water than the first farmers could consume; second, the easily irrigable land was distributed in a broad pattern rather than in a narrow line along the river, meaning that considerable farmland could only be reached by canals that passed through farmland owned by others; and, finally, early leaders may have been sufficiently influential to rally people into collaborative associations. By 1885, agricultural holdings had spread so that the extent of canals on the north side of the river was insufficient for the demand for land. There remained an enormous amount of flat land available that could easily be farmed if water were brought to it. This demand led to the construction of the Arizona Canal, the most ambitious project to date (62-km long). It was the first major canal that went beyond the geographic extent of prehistoric Hohokam canals, thereby bringing more upstream land and land farther from the river under cultivation (Figure 8). The geographic separation of the Arizona Canal from the Salt River channel encouraged the formation of the new town centers of Scottsdale, Glendale, and Peoria north of the river, and the excavation of the Highland and Consolidated canals south of the river sparked the eventual establishment of the towns of Chandler, Gilbert, and Queen Creek. After completion of the Arizona Canal, the first railroad reached Phoenix, easing the shipment of local products to more distant customers. The extent of farmlands continued to grow and, by 1890, there were 100,000 acres under cultivation and almost 11,000 people living in Maricopa County, a marked increase from the 300 recorded in the 1870 census (Sargent 1988). The fact that the Salt River carried more water than the earlier-settled Gila, Santa Cruz, and San Pedro rivers to the south, and that it coursed through a valley with a larger alluvial plain that could be easily irrigated, were important ecological features and permitted Salt River farming quickly to outstrip its neighbors on those other rivers.

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This generally held self-image of a relatively sparsely settled region, able to accommodate rapid growth that knew few limits, altered with the second major triggering event of the Emergent Years: catastrophic floods in 1890 and 1891, followed by a severe drought from 1897-1903 (Table 1: E2; Smith 1986). These serious, but not extraordinary, environmental events threatened the existence of this young farming center, leading the local citizenry to respond on two levels. Locally, many bound themselves together into the Salt River Water Users Association (SRWUA) in 1903, later to be renamed the Salt River Project (SRP) that still manages most of the water distributed in the valley, while some of the more influential citizens took it upon themselves to lobby in Washington for a National Reclamation Act that would transform many regions in the West (Smith 1986; Kupel 2003). These two responses were efforts to overcome the same set of threats, and worked together at different scales to establish lasting changes in the surface-water regime of the Salt River Valley and the its managing political/economic organization. The first response―collective local action—changed the scale of water management in the valley, from individual farmers and small canal companies to basically one supplier of water administered by all users. This semipublic entity in which one acre equaled one vote, reflected a relatively egalitarian attitude; initially, homestead size was capped but, over time, this rule concentrated power in the hands of a small number of large landowners. The second response was a classic cross-scale interaction of pressure produced by local lobbyists leading to national-level changes which, in turn, affected a much larger region and population than first promulgated the pressure (Smith 1986; Mawn 1979; Zarbin 1997). Soon after its formation, the SRWUA convinced federal authorities to build the Roosevelt Dam, 60 miles upstream from Phoenix at the confluence of Tonto Creek and the Salt River. In 1904, a contract was negotiated that promised to repay the federal government the cost of building the dam, using members’ land as collateral. Completed in 1911, the Roosevelt Dam was then the tallest masonry dam in the world and created what was then the largest artificial lake in the world. The Salt River Project (descendent of SRWUA) was the first multipurpose reclamation project in the country; providing hydroelectric power, water delivery, and protection from floods for a growing desert metropolis (Smith 1986; Gammage 1999:24). From the beginning, regional and national perception of the Valley was important to the first settlers, who acted as much like entrepreneurs as farmers. They initiated a long tradition of boosterism of the Salt River Valley by those who lived there and potentially would profit by more people joining them. At first, Swilling and other early settlers who controlled land near the river and the canals that would feed new farms, promoted the region as an untapped agricultural bonanza, but one that took courage to face both the environmental and social uncertainty of the “Wild West” and the extreme climatic conditions. However, with the completion of Roosevelt Dam to control floods and enhance availability of irrigation water during dry years, as well as the admission of Arizona to the Union with Phoenix as its capital in 1912, the Salt River Valley was transformed into a much more developed and predictable place. The mental model of the next generation of boosters was to promote Phoenix as the “Garden City of the West.” Although its citizens and the nation perceived Phoenix as an agricultural city with a future intimately tied to agricultural productivity, more and more of the region’s livelihoods were beginning to be derived from government, finance, and commerce.

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By 1912, much of the landscape of the Salt River Valley had been transformed with 220,000 acres of farming, a population of 35,000 and seven towns scattered across the plain (Figure 4). Although the Salt River was seemingly controlled, in fact, the impact of its variability had been merely altered, not eliminated. Roosevelt Dam controlled annual variations in flow, but multiyear accumulations leading to large flood events, as well as prolonged periods of below-average streamflow still threatened the valley. Moreover, one of the large tributaries of the Salt― the Verde River—enters below Roosevelt Dam, and its flow would remain uncontrolled for 20 more years. The temporal pattern of water availability and threat to valley inhabitants had not been eliminated, only modified. The first two triggering events in the Emergent Years were local, or at most regional, in scope, and primarily related economics to environmental resources and processes. The third event, World War I (Table 1: E3), was international in scope and largely political in origin. With the start of hostilities in 1914, copper prices soared and mining towns northwest and southeast of Phoenix boomed. Their success drove demand for agricultural products and brought vast new income into the state. In addition, the war disrupted access to Egyptian long-staple cotton, essential to the manufacture of airplane fabric, balloons, and cord tires. Local farmers shifted their planting patterns so that Pima cotton became the premier crop, replacing the less lucrative, but soil-enriching alfalfa (Sargent 1988:56). Happily for Salt River farmers, the completion of Roosevelt Dam had changed the agricultural potential of the Valley in advance of this event; a more secure source of abundant water enabled the expansion of agrarian production. By 1920, 75% of irrigated land in the Salt River Valley was devoted to cotton production (Figure 10). Despite the momentary collapse in prices of cotton (and copper) at the end of the war, the emerging national economic prosperity of the 1920s restored the importance of cotton and copper to the Arizona economy. Cotton continues to be the most important crop in central Arizona today. The 1920s also saw the national perception of Arizona evolve to reflect the state’s value beyond agriculture and mining. Phoenix promoted itself as a city where a year-round vacation place and as a Mecca for health seekers, particularly those with respiratory illnesses. Just as affluent invalids had visited the region after completion of the railroad connection in the 1880s, the booming popularity of the automobile encouraged new generations of health and sun seekers to vacation in and move to Phoenix. Local entrepreneurs in the 1920s responded in turn, developing major resorts and hotels and opening commercial airline connections. Tourism would increase and eventually outpace cotton and copper in its contribution to the state economy. The global economic depression of the 1930s strongly impacted Arizona, with an estimated 50,000 citizens leaving the state to search for employment opportunities elsewhere (Sargent 1988:58). All was not grim, however; more than most states, Arizona―and Phoenix in particular―benefited from the New Deal’s federal investments. These policies funded new parks, schools, and street construction, and were responsible for constructing six additional dams on the Salt, Verde, and Agua Fria rivers. All this building activity transformed Phoenix into a regional retailing center and, more importantly, seeded the infrastructure that the enormous demand, soon to emerge in the coming decades, would require (Figure 4). Alongside these accomplishments were New Deal innovations in banking, especially in construction financing. Although rapid growth was not immediate, these innovations created the financial structure and

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initial building experiences for entrepreneurs like Walter Bimson and Del E. Webb, who would introduce a new approach to housing construction a (Figure 11) and marketing as demand increased in the region’s next growth phase (Gammage 1999) The Boom Years By the end of The Emergent Years, much of the foundation for Phoenix’s subsequent growth was in place, but the dreams of local boosters were yet unrealized. The farming system evidenced the hydrological infrastructure and institutional basis that would serve the valley for the next 50 years. With new dams, reservoirs, and canals, agricultural lands had expanded to almost their maximum geographic extent. In the following decades, they achieved their greatest coverage, with only modest extensions of the canals and filling in of previously unused lands. The region’s abundant flat land and easily extended grid of wide streets kept the cost of new residential construction low, yet in 1940, only 65,000 people lived in the city. The triggering event that pushed Phoenix over the threshold and onto a trajectory of rapid, nonagrarian population growth and national prominence, occurred far away and was not engineered by the local boosterism. World War II (Table 1: B1) transformed Phoenix as it did many other parts of the world and can be seen as the triggering event that initiated the Boom Years. Part of this change was due to technology, advances in air conditioning and air travel, and part of it was personal experience—exposure to the area by many pilots and other personnel assigned to bases in the Valley (Gammage 1999:32). Arizona’s year-round clear skies and safe distance from the Pacific coast made it a favored location for air bases and manufacturing facilities and wartime and postwar corporate America responded. Luke Air Force Base opened at the onset of the war, served as temporary home for thousands of young men, and was soon followed by Williams Air Force Base. A growing familiarity with the region increased national awareness of the attractions of Phoenix and led many soldiers to return after the war. The emphasis on military air travel also had implications for the burgeoning commercial air industry. Air travel made Phoenix “closer” to other cities and obviated the need to spend days traveling across the vast, arid Western landscape. Advances in air conditioning technology were also essential to a new conception of life in Phoenix, making it an attractive place in which to live as well as visit. Air conditioning had existed for some time, but it was only after World War II that residential-sized units were produced in quantity. Soon, Phoenix was installing more central air-conditioning systems in houses than anywhere else in the nation. Providing an escape from the intense summer heat, air conditioning transformed a winter haven into an attractive place to live year round (Figure 13). Another key triggering event of the early postwar years occurred in 1948 when Motorola decided to open a manufacturing facility (Table 1: B2) in the region for defense electronics (Sargent 1988). Motorola saw the advantages of a dry climate where workers were happy to relocate and land remained cheap. They soon were among the valley’s most active boosters, and the company expanded until it was the largest employer in the state. Other companies soon established their own high-tech facilities, until the region justifiably became known as the Silicon Desert. By 1955, manufacturing had overtaken farming as the main source of income in the valley, with tourism and home construction growing rapidly.

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Being a manufacturing center with abundant jobs represented the second aspect of the change in the perception of Phoenix, both locally and nationally. Phoenix was no longer just a successful farming center; it had become a city that was a great place to live and home to fast-growing industries. Phoenix benefited from the national postwar movement of people to the Sunbelt and, in many ways, served as one of the icons of this era. In the 1950s, the city grew by over 300%, the fastest of any large city in America (Gammage 1999). Some of that growth came from only annexing neighboring land, but much of it was from newly arrived residents. With the movement of people into the region came a need to build attractive, affordable housing in large numbers. Phoenix was so successful at this that housing, and the suburban ambiance it spawned, characterized the region and attracted new immigrants (Table 1: B3), and we consider it the third triggering event of the Boom Years. Low-cost land, abundant energy, efficiency in construction, and simple design led to the dominance of the ranch house in Phoenix and elsewhere across America. Its single floor, connecting patios, and outdoor space were well suited to the abundant flat land that had been farmed, but was now increasingly being converted into residential developments. Phoenix builders were very good at mass production of this type of home and were pioneers in assembling large tracts of land into integrated housing developments. John F. Long introduced this concept to Phoenix with his Maryvale development and was recognized by a national magazine in 1958 as the number one low-cost homebuilder in America (Gammage 1999:46). Along with new residential developments of ranch houses emerged the concept of the shopping center. These centers were often built at the corner of section-line roads, surrounded by housing and anchored by a grocery store with abundant surface parking. These new patterns of growth led to a major transformation in the urban environment. Farmland that had dominated the landscape continued to thrive, but the Valley was being converted into new housing developments. The seven dispersed towns separated by farmland and open space had now merged into a relatively continuous spread of streets, businesses, and housing. Empty land was still found within this urban core and a broad fringe area with intermingled farms and housing developments, but the settlement pattern had changed to that of a vast urban sprawl (even by the mid-50s) surrounded by a broad band of farmlands, all set within the bajadas and mountains of the upper Sonoran Desert (Figure 4). Farmland in Maricopa County reached its peak of 550,000 irrigated acres by 1953, an extent that held relatively constant for the next 25 years, despite more than doubling of the urban population. Cotton remained the primary crop, while wheat and orchards increased in importance. Interesting changes were evident in the local farmlands. Because farms near the center of the Valley were being sold and converted into urban areas, new lands were being irrigated, often at the fringe of former farmland or in areas that had been undeveloped in the past. These changes were enabled partly by the completion of Waddell Dam on the Agua Fria in 1927 and Horseshoe Dam on the Verde River in 1948 and partly by the great increase in groundwater pumping that allowed for irrigation in areas away from the canals. The growth in irrigated acres during the 1940s and the maintenance of farmland acreage in the face of expanding cities during the 50s, 60s, and 70s meant a filling-in of farming areas with more continuous irrigated lands. The 1950s also saw the greatest number of farms in Maricopa and Pinal counties, peaking at over 7,500 farms as compared with just under 3,000 in the region both at the completion of Roosevelt

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Dam in 1911 and in the most recent agricultural survey in 2002 (USDA 2002). Much of the variability in farm numbers comes from Maricopa County, where agricultural growth exploded in the early years (from 1,000 in 1900 to 6,500 in 1950), decreased dramatically as the city consumed the nearby farms, and leveled off at about 2000 farms from 1970 until the present (Figure 14). In the case of Pinal County, the number of farms did not vary as much as their sizes. By 1940, Pinal contained its maximum number, about 1,300, a figure that slowly and steadily has decreased until the present-day 800. Interestingly, the average farm size in Maricopa has changed gradually—from only a few hundred acres from 1900 to 1950 until the 1950s and 1960s when the average grew to just over 1,000 acres and now is back down to about 300 acres (Figure 15). This number contrasts sharply with Pinal County where there were always fewer farms, but they quickly grew as the depression ended and the boom began up to an average size of almost 5,000 acres throughout the 1960s and 1970s. In the last 20 years, Pinal County farms have become smaller, but they still average more than double the size of those in their neighboring county. Clearly, the urban pressure has never been substantial in Pinal County and, in fact, some Maricopa County farmers who sold their holdings shifted their efforts to farms in Pinal. The relatively large number of small farms that have characterized Maricopa County reflects the originally small homestead size and the fact that many were family farms and often run by people in the city involved with other pursuits. The maintenance of numerous small farms into the latter-20th century also relates to the importance of land speculation; those who owned the farmlands hoped to sell their land at a high price. Add a short paragraph on major crops and major livestock (need another new figure?). During this era, especially the 1940s and 1950s, the climate experienced an extended dry cycle with below average streamflow in 17 of the 20 years. This long, dry cycle could be considered another sustained triggering event, pressuring the system. Although drought concerned some, the common perception was that technology could meet the challenge. Without derailing the meteoric population growth of the era, water needs were met by dramatically increasing the amount of groundwater pumped (Figure 16) and making the water distribution system more efficient. Major canals were lined to limit water lost to percolation, and secondary canals, especially those in urban areas, were covered or put into pipes partly to save water from evaporation and seepage and partly to enhance the urban nature of the landscape. Diminishing the amount of water “lost” from the canals seriously impacted the ecology of the canals and the manmade riparian areas that had dominated the canal-laced landscapes during the Emergent Years. Canal banks no longer supported trees and shrubs, as all their water was reserved for human use. Within the growing cities much of that water use was for mesic landscaping, where Bermuda grass lawns, fast-growing trees, and exotic species such such as the African sumac tree, citrus trees, and the Mexican fan palm dominated the new master-planned subdivisions (Gammage 1999; Weworski 1999). The ecological imprint of urban growth is revealed in myriad ways. First, irrigated farmland fills in and is pushed out from the center to the practical limits of gravitation-fed irrigation and soil. Second, the patchwork of towns interspersed within a largely agrarian landscape is transformed into a large urban core with mesic landscaping, with a fringe where farms and housing tracts intermingle, all surrounded by a periphery of farmland where the topography allows, and desert beyond that. Third, efforts to make water use more efficient would progressively transform canal ecosystems from a more streamlike system with a riparian zone to one more like an open pipe

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where water is confined for human consumption. This sequence has occurred because the shared perception of most people is that in the competition for water use, human-directed uses have a higher value than non-human directed uses. Fourth, and finally, demand for water is so great that all available water is withdrawn from the Salt River before it passes through Phoenix. What was once a river with regular flow and associated wetlands had been transformed into a dry gravel strip that only held water during flood episodes. Over the span of this narrative, priorities among human-directed uses may have changed order, with mining, agriculture, and now municipal being the most highly valued, yet at all times, non-human uses are valued more than others. How did changes in the landscape and activities of inhabitants alter their perception of the urban ecosystem in which they participated? First, the hydrology of the irrigated agriculture was becoming more engineered and less visible to most citizens. Canals were being lined and losing their riparian appearance, other canals were placed underground, while groundwater was extracted to supplement and, in some places, replace surface water. As the city limits spread, an increasing number of citizens did not have contact with farmland or even see it as part of their region. In tandem with this visual separation, farming lost its paramount position in the local economy and politics. Manufacturing was number one, and other industries such as tourism, construction, retail, and government employment were soon to surpass agriculture as well. It was not that farming was failing—quite the opposite; during the Boom Years, farming was booming as well. With the introduction of more chemical fertilizers, farm machinery, and supplemental groundwater, the productivity of most crops grown in the region more than doubled in relation to national averages (Figure 17). The key was that farming interests were still seen as important, but only as one segment of the overall interests of Phoenix. For most people, especially the boosters, Phoenix now represented industry, affordable housing, a higher quality of life, and the excitement of (and profit to be derived from) growth. Phoenix was now the largest city in the Southwest and the fastest growing in the nation. Its boosters promoted a “can do” attitude and were able to push through Congress the ambitious Central Arizona Project to build a 300-mile canal to bring Colorado River water to Phoenix and Tucson. Residents’self-image was also on the upswing. For example, Phoenicians insisted on passing in 1958—despite the reticence of the Board of Regents—a referendum to change the name of the local college from Arizona State Teachers College to Arizona State University (Gammage 1999). Southwest Metropolis The past 30 years has seen Phoenix grow to become the fifth-largest city in the nation and the fastest growing among the largest cities (US Census 2002). It is now the undisputed central city of the Southwest with the sixth-busiest airport in the nation, more than double the number of people of any other city in the region, and a growth trajectory that has not faltered even in tough economic times. What perceptions have driven that growth and what triggering events have occurred to modify these perceptions and trajectory? Unlike the Boom Years, the first triggering event of this era was not a specific “event” of short duration, but more like a continuous series of pressures and opportunities. First, the region continued to benefit from the migration of interest, companies, and people to the Sunbelt from America’s rustbelt (Table 1: SM1). Jobs, affordable housing, an outdoor lifestyle, all brought people to Arizona. Second, Phoenix has the highest rate of home ownership among the large cities of America (Brookings Institute 2003). Finally, there was also a shared vision of Phoenix

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as a place not only to get a job, but to get rich quick, as reflected in wide participation and frequent success of real-estate entrepreneurs and private citizens turned speculators. This continued immigration, especially of people who hoped to own their own homes, meant that new houses would need to be built in unprecedented numbers (currently over 50,000 per year). The spread of new housing into former farmlands continued apace, but was soon equaled by the conversion of former desert terrain into residential developments—one of results of this triggering event that transformed the regional landscape in new ways. Real-estate entrepreneurs encouraged this pattern. They sought to purchase large tracts of inexpensive land, often looking well beyond the current fringe of the city, developing them into integrated, master-planned communities (Brooks 2004). This leapfrog pattern of development beyond current city limits had the effect of increasing the rate of spread and only encouraging infill just behind the leapfrogged development rather that staying within current urban limits and increasing core densities (Figure 4). The shift to building in the desert did not yield surplus water that could be dedicated to the new housing developments, as had the conversion of previous farmland. The tendency when old farms were sold for housing had been for a few farmers to retire, but more often to establish new farms on unused Maricopa County lands or to move south to Pinal County, hence maintaining total farming acreage in the region. This continuing need for agricultural water, added to the demand of the growing urban population, led to developing tensions about water supply in the 1970s, despite relatively favorable precipitation patterns. The perception, especially to outsiders, was of Arizonans disregarding appropriate limitations on water use in their desert city. The focus became falling groundwater levels, due to 30 years of higher rate of withdrawal than recharge. Possible subsidence, extra expense of drilling wells and pumping water from greater depths, environmentalists’ concerns of diminished water for native vegetation, and the ultimate fear of just plain running out of water were considerations for differing segments of the local population, part of their shifting mental models of life in the desert. These fears led to the second triggering event of the era: Secretary of Interior Cecil Andrus threats to stop funding the Central Arizona Project (CAP) unless the people of Arizona took seriously the maintenance of groundwater levels (Kupel 2003). CAP was an expensive, federally funded project to bring Colorado River water to central Arizona, regarded locally as “final” insurance against running out of water. Under enormous political pressure from then-Governor Bruce Babbitt and others, rival interest groups cooperated in creating the Groundwater Management Act of 1980 (Table 1: SM2), which transformed expectations and actions in terms of water use. The goals were to balance groundwater extraction with the rate of natural recharge by encouraging surface-water use, prohibit new farms or increased consumption by existing farms in the Phoenix and Tucson regions, and set conservation standards for municipal users (Kupel 2003). The Groundwater Management Act (GMA) provoked diverse reactions. First, prohibiting irrigation of new lands around Phoenix meant that the maximum extent of farmlands was fixed at 1980’s boundaries; hence, total irrigated acreage in the region would diminish as urbanism swallowed farms. This trend has continued over the past 20 years (see Figures 19 and 19a) and most farmers on the original SRP lands are expected to sell their farms for residential construction by 2010. Some of these farmers have moved their operations to Pinal County where

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the Act’s restrictions are different, but many have ceased to farm, diminishing the state’s overall agricultural acreage. For the remaining farmers, limitations on water use—allocated by acre, not by crop—has encouraged them to select crops with high economic value per quantity of water used, such as seed crops and vegetables. Alfalfa, alternatively, requires more irrigation but less labor and capital, and is preferred by many farmers with sufficient water allocation who are waiting to be bought out. Another reaction came from lawyers and managers aiming to rationalize water consumption without jeopardizing rapid growth in Arizona’s cities. The regulations they devised for the GMA allow developers or municipalities not adjacent to canal water sources to join an association (replenishment district). This arrangement permits them to withdraw groundwater in their locality in return for payment to CAP, whose water is purchased and pumped back into the ground elsewhere, in an attempt to replenish the aquifer. Although the principle here seems sound, we do not have experience withdrawing this stored water and do not know the actual result in quantity or water quality. The goal of the GMA was to reach “safe yield,” where the amount of water entering the aquifer roughly equaled the amount withdrawn. The assumption behind these regulations was that water allowed to seep into the ground in one part of the basin would be stored there for later extraction anywhere in the basin. Not only is this a legal regulation, but it is a widely held perception of water managers, providing the rationale for new residential communities as long as the developers and residents pay for the surface water available in the CAP. These legal institutions provide a mechanism for continued urban development into areas far from the current surface-water infrastructure, in some ways contradicting the law’s intent. These arrangements usually affect desert locations and allow leapfrog developments to remain practical even under GMA guidelines (Figure 4). The third triggering event of the Southwest Metropolis Years involves the changing demographic character of the city. In a study conducted by the Brookings Institution (2003:17), it was found that Phoenix has a relatively low number of ethnic minority residents (44% versus 62% for all cities in the study), yet this number is growing rapidly (2003:17). Between 1990 and 2000, Phoenicians of Hispanic origin increased from one-fifth to one-third. We identify this as a gradual, but significant, change to the urban fabric, and a triggering event of as-of-yet to be determined impact (Table 1: SM3). How the changing ethnic mix of residents will affect decisions about water use, farming, and related economic and quality-of-life issues is difficult to determine; however, it will tinker with the mental model of our region. The very changes in flows of basic resources that have made Phoenix hospitable and economically successful have radically altered species composition in the city from what occurs in the surrounding Sonoran Desert. Supplemented resources, particularly water, increase and stabilize productivity, dampening seasonal and interannual fluctuations in species diversity, elevate abundances, and alter feeding behaviors (Faeth et al. in review). Relative abundances have greatly increased select native and nonnative generalist bird species (sparrows and doves), ground arthropod generalists (ants, springtails, and mites), plant-feeding arthropods (aphids, white flies), generalist pollinating arthropods (honey bees), jumping spiders (Lycosidae), and fence lizards at the expense of more specialized species in these respective groups (McIntyre et al. 2001; Shochat et al. 2004b; Hostetler and Knowles-Yánez 2003). Most of these changes in species abundances have not been caused by purposeful human extirpation, but are due to

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conversions of habitats from desert to agriculture and urban residential with the accompanying changes in water and other flows. Paragraph on Crops? Several patterns that characterize the Southwest Metropolis years impact the environment of central Arizona and the agrarian and urban landscapes of the Phoenix region. First, a number of actions have allowed and perhaps encouraged the continued geographic spread of urban development. The Groundwater Management Act and subsequent legal institutions of replenishment districts and water-banking authority have enabled the construction of new housing developments in areas that were not traditionally served by surface water sources. During this era, voters underwrote the vast expansion of the region’s freeway system. The migration of primarily young people from other states and from south of the border continued at a rapid pace, driving the demand for new housing. Second, the Groundwater Management Act, which prohibited new agricultural uses of water and promulgated a pricing strategy for new residential water that subsidized the remaining farmers’ use of surface water, has stabilized and, in some cases, gradually replenished local aquifers. As a result, during 1980-2000, irrigated acreage in Maricopa County has diminished by more than 50% while the overall water use has remained relatively constant despite a doubling of population. Further easing the potential water problems was the opening of the Central Arizona Project canal in 1988, which brings over 1 million additional acre-feet of water per year to the Phoenix-Tucson region (Figure 19b). Although the availability of supplemental water has allowed the continuation of mesic landscapes,the combination of lawns and broadleaf trees are largely confined to older neighborhoods at the center of the metropolitan area and scattered developments in newer sections. Desert plant communities still prevail in their native locations outside the city and interestingly have been maintained in various urban locations whose elevations are above the floodplain (Figure 20). In an effort to re-create desert vegetation in newer urban developments, landscapes have been designed that provide aesthetic aspects of a Sonoran Desert habitat, but with a mixture of native and exotic plants, gravel surfaces, and hoped-for low water requirements. Our own LTER research has shown that homeowners with these re-created desert landscapes sometimes, but not always, use less water than their mesic neighbors (Martin et. al. 2001). Surveys have also shown that the preferred landscape form for most Phoenicians is pattern that combines mesic and xeric areas in what we refer to as an oasis design and it does not use significantly more water than a completely xeric yard. These developments have led to a strange paradox in public perception of water in central Arizona. On the one hand, the lack of rainfall (an average of <200mm per year), the dry riverbeds that course through the city, and the surrounding desert landscapes encourage residents to worry about water availability. This fear has caused restrictions on use of potable water for golf courses and decorative lakes, hence encouraging the growth of water reuse in selected situations in the valley. Xeriscape landscaping in public areas has become the norm and several water-treatment plants are using a wetlands approach that promotes groundwater recharge. Nevertheless, concern about the adequacy of the water supply has not invoked conservation restrictions on individuals or serious pricing disincentives on residential or industrial water use. Moreover, despite the limitation on new decorative lakes, the largest of them all—Tempe Town Lake (89 hectares)—was constructed during this era (Figure 21). Contrary to public perception,

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water managers and those who are most involved with water decisions do not believe there is a local water problem, nor is one likely to develop in the near future! Hence, they are not inclined to push for serious legal requirements for residential conservation or limits on new residential construction given the potentially dire effects a “water scare” would have on public perception and possibly on the economy. But is there enough water to support continued population growth and relatively high per capita consumption? And will the water that we do have available be of sufficiently high quality for residential use? We do not know, and new research and data compilation is necessary to answer these questions. Into what appeared to be a relatively sanguine situation, a fourth triggering event occurred, this time prompted once again by an extreme, but not unforeseeable climatic pattern—drought (Table 1: SM 4) Since 1999, there has been a period of very low rainfall and associated surface flows in the region. This period came after a five-year span of relatively low rainfall, meaning that the reservoirs were already low when the intense drought began. The reservoir behind Roosevelt Dam, the main repository for storing Valley water, fell to 12% of capacity and the two largest reservoirs on the climatically “independent” lower Colorado River system were down about 50%. Although this was not an extraordinary situation historically, it has attracted media attention, resulting in front-page coverage on a number of occasions (Arizona Republic 2005). Ramifying this perception was the fact that, for the first time, SRP (which relies on local reservoirs) cut its water allocation to customers by 33%. Municipalities, having adequate financing, were able to reallocate their water sources and did not pass on this water restriction to customers. However, cuts to farmers, operating at the margin of economic profitability, led them to respond by not planting some of their lands. The recent drought and reduced SRP deliveries, occurring alongside considerable media interest in the implications of unchecked urban growth, have sparked discussion about the potentially dire long-term consequences of rising and inflexible (i.e., urban) water demand in an arid environment. Responding to heightened public concern, Arizona Governor Janet Napolitano, created a Drought Task Force that received the unprecedented assignment of developing plans for dealing with potential water crises in the state. Would the change in public perception during this drought foster substantial changes in public policy on growth and water use when it had failed to before? Those anxious about growth and quality-of-life issues may combine with advocates of water conservation to prompt serious policy changes, as well as modify the individual’s regard for water resources. In addition, Arizona State University’s Decision Center for a Desert City, funded by The National Science Foundation is analyzing the decision processes used to plan and manage water resources and urban growth and assist water-resource managers as they plan for increased urbanization in the region. However conservation-minded the reader may be, one should have caution about what you hope for. If serious water conservation strategies are imposed, the first to suffer will be the remaining natural riparian vegetation, followed by public-landscaping vegetation, and eventually residential vegetation. In Phoenix’s environment, rainfall supports only a small proportion of the current urban vegetation, most of it being exotic and requiring purposeful supplements. With virtually all surface water flow taken out of its natural courses and managed towards other objectives, an extreme scenario of water conservation would be for the urbanized region to be changed from an oasis to a landscape largely devoid of plants unless people converted their landscaping to

21

location-appropriate native vegetation at appropriate densities as in Figure 2. Will this happen? We doubt that the citizenry will either convert to a totally native regime or give up their urban oasis, but what environmental, economic, perceptual, and legal changes will have to happen to avert this course of events? Prospects for Conservation How does one join the growth patterns of a burgeoning Southwest metropolis with the need to conserve key habitats, preserve ecosystem function, respect biodiversity, and educate a largely urban population as to the rewards of being environmentalists? Several pathways are possible for funding or mandating conservation activities in central Arizona—public, private, or some combination. Arizonans are pursuing all three approaches, but combination approaches are clearly gaining the most momentum. Before examining these funding streams, it is useful to address the more fundamental issue in central Arizona, “what do we want to conserve?” As suggested above, traditional environmentalists are loath to apply their energies to conserving the urban/agrarian landscapes of Phoenix and its environs. Part of the problem is that farming transformed so much of the land; land either remains in that use or has been further transformed by urbanization. This trajectory accounts for all of the flat, low-lying terrain within reach of canal irrigation. Flat areas beyond farming have what aesthetically appears to be uninteresting vegetation and may have been denuded by cattle grazing. Beyond those areas are mesas, ridges, and small mountain chains with potentially more aesthetic appeal that have been the focus of conservation efforts in other parts of the state. Much of that land is under public ownership and, to some degree, is being conserved as county parks, state lands, or National Forest. This gradient logically leads local conservationist to focus on the small tracts of uplands that are in private ownership, beyond the current reach of urbanization. This approach has been done largely through the creation of local land trusts or the efforts local chapters of national organizations such as The Nature Conservancy. Land trusts often emerge from the efforts of a few, dedicated individuals who seek to preserve a particular landscape from development. One of the most successful in our region is the McDowell Sonoran Land Trust, which raised private funds and eventually placed a bond issue on the municipal ballot in Scottsdale that passed by a 73% margin. Founded in 1990, a grass-roots organization working to preserve, protect, and celebrate the McDowell Sonoran Preserve. They contribute funds to the City’s efforts to expand the preserve, which is currently encompasses more than 17,000 acres, with plans to acquire over 19,000 additional acres (once these purchases are made, the Preserve will total 57 square miles). Similar efforts to conserve land, but through a private land trust, are occurring around the periphery of the Superstition Wilderness Area. Another example is the Desert Foothills Land Trust, which seeks to preserve tracts of land at the northern periphery of the metro area. Each endeavor has been successful at preserving land at a small scale and to then broaden their reach, sought partnerships with public entities or access to public funds through ballot initiatives. Recent conservation achievements have received direct support from municipal or state leaders. The Phoenix Mountain Preserve grew out of a grassroots movement in the early 1960s in which citizens were deeply involved. As the scale of the opportunities increased, it became apparent to city leaders that a more formal approach would be beneficial. A Phoenix Mountains Preservation Council was formed and sparked a momentum for city leadership, Mayor Skip Rimza in

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particular, to spearhead a ballot initiative to earmark a small portion of the city sales tax for the purchase of lands the would expand and, in some cases, connect the various mountain preserves. Another initiative was enacted by Arizona’s relatively conservative state legislature in 1996. The Arizona Preserve Initiative was designed to encourage the preservation of select parcels of state trust land in and around urban areas for open space, scenic beauty, protected plants, wildlife, and archaeology to benefit future generations. This bill was a good start, but it did not come with its own funding, leaving a tremendous financial burden on any organization or municipality that wanted to purchase parcels for preservation. A ballot initiative was passed two years later that allocated significant state funds for this purpose, but only if matching funds could be raised. Because of this burden, the bill has not led to large-scale land preservation and there is a still strong sentiment that more must be done to preserve key parcels of state land near to urban areas. Key business and environmental leaders began to meet unofficially in an effort to forge a compromise strategy for attaining the sometimes conflicting goals of various stakeholder groups. Among the stakeholders were real estate developers, who wanted to insure a steady stream of new land available in urban areas for future construction; educators, who stood to reap maximum financial benefit from the sale of state lands (whose proceeds go to education); the business community, who wanted to see new housing continued to be built, but also wanted to enhance the quality of life by preserving open space to attract new industry; environmentalists, who were primarily concerned with rural land preservation; and ranchers who wanted to maintain their inexpensive leases of rural state lands. Interestingly, the most difficult conflict was between the environmentalists (most of whom dropped out) and the ranchers who eventually scuttled the tentative deal after two years of negotiations. The other unlikely opponent of inexpensive land for conservation was the education lobby who saw this as diminishing their long-term financial benefit. A smaller group that focuses solely on urban lands is still meeting and there is hope for a compromise that will lead to the immediate preservation of substantial tracts and an easier method for securing additional land for preservation over time. An even bolder approach is being implemented just south of our study area, in Pima County around the city of Tucson. In May 2004, voters approved the Sonoran Desert Conservation Plan which integrates all natural-resource protections and land-use planning activities into one plan rather than keeping these activities separate and often conflicting. The Pima County Board of Supervisors initiated the discussions six years earlier and insisted that the science-based planning should be the top priority rather than political considerations. There has been widespread participation with citizen’s steering committee of over 80 members, over 400 public meetings, and more than 150 scientists contributing their expertise. In addition to the comprehensive plan, the ballot issue funded a bond authority of $174 million to support conservation-land purchases. Although supporters might point to the broad participation as key to the success of this initiative, it needs to be recognized that land developers are not against conservation as much as they are anxious to have a steady stream of reasonably priced land available in desirable locations. Under the threat of possible limitations due to an endangered species, the pigmy owl, developers saw it in their best interest to find a way that both conservation and development could succeed. The success of the Sonoran Desert Conservation Plan and its accompanying bond issue has emboldened some Maricopa County residents to consider a similar initiative. The Nature Conservancy, who has been looking for a way to capture the interest and financial support of

23

area residents, is in the early planning stages of developing such a plan. It is already being discussed whether ASU scientists involved in the CAP LTER and the Ag Trans project could aid in developing science-based plans for conservation within the county. Can a comprehensive plan in a rapidly urbanizing region like central Arizona aid in mitigating habitat fragmentation, ensure watershed integrity, and encourage remaining biodiversity? These important ecological questions require a rational, comprehensive approach to conservation and development needs, one that understands how urbanization and human activities can be guided to maintain maximum environmental values. At the same time, our own work on this case study suggests additional lines of inquiry that could lead to innovative approaches to conservation. First, high-priority endangered habitats or threatened species―the target of traditional conservation efforts―should be identified and strategies for their protection devised. Given the long-term human use of landscapes near the metropolitan area, it is unlikely that there will be significant quantities of these types of targets. Second would be landscapes that could be protected or restored so that they could serve as substitute habitats for threatened species, once again provide substantial ecosystem services, and offer aesthetic rewards to the visitor. This research area has great promise, especially considering the federal funds available for local efforts to provide replacement habitats for the Southwestern willow flycatcher and other endangered species. Of special interest here would be the recognition that the restoration was not re-creating a truly “natural” habitat, but a designed habitat where the designers decided what species, food webs, and material flows to favor in the restored habitat. We believe this is an essential exercise for modern conservationists and could lay the foundation for a rational approach to land transformation in the coming generation. The third line of inquiry is a variation of the second, but where education and recreation were the primary objectives. As the globe becomes more urbanized and as many of those urban residents have medium or low incomes, it is likely that most citizens will not experience “nature” that is distant from their homes, such as national parks or wilderness areas. Yet, for a wide variety of reasons it is essential that meaningful environmental exposure is available to them. We need to seek readily accessible landscapes that can be protected or restored to a point where meaningful environmental experiences can be had. Because access is a priority, compromises will be necessary and supplemental inputs will have to be made continually to maintain valued aspects of the ecosystem. The fourth type of conservation target derives directly from Ag Trans research and attempts to integrate the human and ecological aspects of landscape transformation and function. At one end of the spectrum, it would mean preserving historically important human-nature relationships such as early farms, ranches, and rural towns. This effort is already evident in culture parks and historical monuments. The landscapes that we do not think are sufficiently targeted are those that reflect the “struggle” between people and natural forces in the environment. An example from our narrative are traditional irrigation canals. At first the element of having to follow the natural topography and soils in the construction of the canals that are little more than supplemental streams. Next, is the way natural forces take hold of this human transformation and infest it with plants and fish creating an anthropogenic riparian habitat unlike anything in a pre-human world

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or human designed. Yet, in microcosm, this example represents much of the world we are creating and offers a classroom for human-environmental interactions. Conclusion that takes the reader from a discussion of conservation to a broader discussion about agrarian landscapes and their legacies in rapidly urbanizing central Arizona…. Acknowledgements This research has been supported by NSF Biocomplexity in the Environment (DEB-0216560), NSF CAP LTER (DEB-9714833), and McDonnell Foundation grants. Many people have contributed to the thinking and data collecting built-upon by this chapter. Of special note has been the work of Lauren Kuby, Anne Gustafson, Sam Schmieding, David Bild, Glen Stewart, Nancy Grimm, and Grady Gammage, Jr.

25

Figure List

1. Boundaries of the study site (CAP LTER and Ag Trans).

2. Turner vegetation map (forthcoming)

3. Population rate of growth Phoenix vs. national trends.

4. Changing urban land sources for new urban lands in the CAP LTER study area.

5. Conceptual model of Ag Trans project.

6. Map of canals: prehistoric and modern

7. Map of vegetation communities based on Ingalls’ 1867 map for the General Land Office

(GLO) survey.

8a. Regional land use, 1912.

8b. Regional land use, 1934.

8c. Regional land use, 1955.

8d. Regional land use, 1975.

8e. Regional land use, 1995.

8f. Regional land use, 2000.

9. Price and acreage of cotton.

10. Groundwater pumping and streamflow.

11. Productivity of cotton, local and national.

12. Irrigated acres: Maricopa and Pinal counties.

13a. Water users for the Phoenix Active Management Area.

13b. Water sources for the Phoenix Active Management Area.

14a. Vegetation communities for the CAP LTER study area, based on 200-Point Survey.

14b. Urban vegetation community for the CAP LTER study area, based on the 200-Point Survey.

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Figure 1. Boundaries of the Central Arizona-Phoenix Long-Term Ecological Research (CAP LTER) and Agrarian Landscapes in Transition (Ag Trans) study sites. The Central-Arizona Phoenix (CAP) Ecosystem encompasses an area of 6,400 km2, while the Ag Trans study area encompasses 37,993 sq km2.

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Figure 2. Maricopa County population and population rates of change by decade for Maricopa County and the US, 1910-2000. Maricopa County roughly corresponds to the Phoenix metropolitan area.

186,193

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Figure 3. The growth of urban settlement in the Phoenix region, 1934-1995.

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Figure 4. Historic land-use maps. Figure 4a. Regional land use, 1912. Figure 4b. Regional land use, 1934.

Figure 4c. Regional land use, 1955. Figure 4d. Regional land use, 1975.

Figure 4e. Regional land use, 1995. Figure 4f. Regional land use, 2000.

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Figure 5. Turner Vegetation Map (forthcoming) Figure 6. Map of case study area showing parks, monuments and wilderness areas. Figure 7. Historic postcard circa ??? from Arizona Historical Foundation.

Figure 8. Map of prehistoric and existing canals located within the CAP LTER study area. Source: Salt River Project

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Figure 9. Pictorial portrayal of the unhospitable Southwest

Figure 10. Map of vegetation communities based on Ingalls 1867 map for the General Land Office (GLO) survey.

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Figure 11. Price and acreage of cotton in Maricopa County.

Figure 12. Typical track dwelling.....

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Figure 13. Chamber of Commerce advertising, circa 19555. Arizona Historical Foundation

Figure 14. Total number of farms in Maricopa and Pinal counties, 1900-2002

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Figure 15. Average farm size for Maricopa and Pinal counties, 1900 to 2002.

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Figure 17. Productivity of cotton, local and national.

Figure 18. Irrigated Acres: Maricopa and Pinal Counties.

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Figure 19a. Water Users for the Phoenix Active Management Area (AMA).

Water Demand by Sector 1980-2000: Phoenix AMA

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Figure 19b. Water Sources for the Phoenix AMA.

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Figure 20. Vegetation communities for the CAP LTER study area, 2000. Source: 200-Point-Survey.

Figure 20. Tempe Town Lake